package udp;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * Author:  LiuTao
 * Version: 1.0
 * Date:    2024-04-07  15:27
 */
public class UdpEchoServer {
    private DatagramSocket socket = null;

    public UdpEchoServer(int port) throws SocketException {
        socket = new DatagramSocket(port);
    }

    //服务器运行逻辑
    public void start() throws IOException {
        System.out.println("服务器启动！");
        while(true) {
            //每次循环处理请求---响应的过程

            //1.读取请求并解析
            DatagramPacket requestPacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(requestPacket);
            //读到的字节数组转换成字符串
            String request = new String(requestPacket.getData(),0, requestPacket.getLength());

            //2.根据请求计算响应（回显服务器不需要）
            String response = process(request);

            //3.把响应返回客户端 构建一个响应对象
            DatagramPacket responsePacket = new DatagramPacket(response.getBytes(),response.getBytes().length,requestPacket.getSocketAddress());
            socket.send(responsePacket);

            System.out.printf("[%s:%d] req: %s resp: %s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);
        }
    }

    public String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        UdpEchoServer server = new UdpEchoServer(9090);
        server.start();
    }
}
